#include <stdio.h>

int factorail(int n)
{
    if(n == 1 || n == 0)
    {
        return 1;
    }
    else
    {
        return n * factorail(n - 1);
    }
}

int main()
{
    int num;
    printf("%d", factorail(num));
    return 0;
}